Strands of conductive metals, such as aluminum and copper and their respective alloys, are often produced to any desired length and shipped in coils for use in electric transmission lines, for example. A process for this purpose, such as the Properzi process, comprises continually feeding a stream of molten metal into a peripheral groove near the top of a chilled casting wheel as it rotates, covering the part of the groove where the metal solidifies with a traveling belt over the groove, removing the solidified metal from the casting wheel and passing it through forming rolls while under tension, and coiling the resultant metal strand.
Feeding the molten metal onto the casting wheel groove requires care. Overfeeding can overflow the groove and halt the process, and underfeeding can cause voids in the solidified strand which can halt the process by breaking the strand during rolling. Conventional equipment for the process comprises an upper tundish to receive an incoming stream of molten metal; a lower tundish receiving molten metal through a downspout from the upper tundish; a trough extending laterally from the lower tundish to convey molten metal into the casting groove; and a baffle beneath the spout which floats on the molten metal in the lower tundish. As the level of molten metal in the lower tundish rises the baffle rises to reduce the inflow from the spout, and as the metal level falls the baffle moves away from the spout and thereby increases the inflow of molten metal from the spout, thus tending to automatically keep the level reasonably constant under a given set of constant operating conditions.
While a floating baffle works successfully under a given set of operating conditions, it is not adjustable during operation to vary the rate of outflow from the spout independently of the level of molten metal in the trough which feeds into the casting groove; for example, when the level should be higher to more entirely fill the groove, or when the speed of rotation of the casting wheel is altered.